How to handle missing values in crossprod in R?

Question

I am trying to calculate the sum products of two vectors, but there is NA in one of them.

crossprod(c(4.5,4,4,3,NA), c(1,5,4,1,1))

In calculating, I want to treat NA as a zero. But in original data frame,I still want to keep it as NA for further data processing. Any hint will be appreciated.

Answer 1

If your cross product is more complex than a sum, you can define a new function which replaces NA in the arguments:

crossprod.replacena <- function(x, y, val=0) {
                                  crossprod(replace(x, is.na(x), val), 
                                            replace(y, is.na(y), val)
                                  )
                        }

Or you can call replace on your arguments without defining a function, as replace does not modify its arguments.